It is well-known that aircraft engines are lubricated by a set of pumps. Some of these, the high-pressure pumps, ensure the pressurisation of the oil taken from the tank that is then supplied to the engine components to be lubricated, for instance to the chambers of bearing supports. Other pumps, the recovery pumps, ensure the recovery of the oil collected at the low points in the engine and its return to the tank by an upstream circuit. In general, these pumps are either operated by a common shaft in a “lubrication assembly” or individually distributed in the engine. Typically, a high-pressure pump (over about ten bar) that supplies the jets and several recovery pumps on the same shaft can be found, as well as for instance an additional recovery pump for the oil from another equipment. preferably located towards the bottom of the oilpan of the lubrication assembly so as to avoid as much as possible the adverse effect on its fixings, which would be a result of the shearing forces caused by the vibration of the engine.
The lubrication assembly is generally provided with a number of safety devices in the form of valves providing adequate closing or opening. These may be of three types:                a valve that opens in the event of excess pressure in the oil circuit;        a bypass valve that opens when the filter is blocked;        a valve that closes the oil intake in the filter when the latter is to be dismantled, without completely draining the lubrication circuit.        
According to the prior art, each separate valve housing requires special machining in the oilpan of the lubrication assembly, which makes the shutting and filtering device bulky, complicated and expensive to manufacture.